Alloy for use in the cracking of petroleum



Patented Apr. 25, 1933 UNITED STATES PATENT OFFICE VERE IB. BROW'NE, O'F BRAGKENREGE, PENNSYLVANIA No Drawing.-

This invention relates to an alloy that is resistant to the corroding influences of many reagents at elevated temperatures, and is particularly useful in connection with apparatus used in the cracking of petroleum.

An object of the invention is to produce an alloy that is resistant to intensive corroslon at elevated temperatures.

A further object of the invention is to produce an alloy that is resistant to the corrosive reagents generated in the oil cracking processes.

A further object of the invention is to produce a relatively cheap alloy that may be fabricated into various articles, such as tubes, shapes, etc., and that retains a high tensile strength at elevated temperatures, and is capable of withstanding high internal pressures at such temperatures, and that is resistant to corrosion at such temperatures.

Alloys suitable for the manufacture of tubes and other shapes to be used at elevated temperatures in chemical processes are expensive, and do not always possess the combined properties of tensile strength and resistance to corrosion under the conditions ex isting in those industries. Lower priced alloys have, in many cases, proved to be more expensive in practice than the higher priced alloys, in that they have a reduced life, and

in some cases have not possessed a desired mechanical strength at the elevated temperatures.

In the petroleum cracking industry, considerable difficulty has been experienced in obtainin an alloy which is relatively cheap, has a su ciently high tensile strength at elevated temperatures, and is resistant to the corrosive reagents that are developed during the cracking process at the elevated temperatures.

As a result of researches with alloys that may be applied to the uses referred to above, it was discovered that alloys containing chromium, copper, aluminum, and the balance of iron, with or without the presence of minor quantities of other alloying elements, in the general proportions of from about 4 percent to about 8 percent of chromium, from about 4 percent to about 1 percent of copper,

Application filed February 7, 1930. Serial No. 426,596.

from about ,4; percent to about 1% percent of aluminum, with or without minor quantities of other elements as above noted, and the remainder of iron, possesses the above enumerated desired characteristics to a greater extent than other low priced alloys known at this time; and that tubes and shapes made of such alloys may be successfully used in high-temperature high-pressure chemical processes in which the alloy is subjected to in tensive corrosive action. As a result of experience in the petroleum cracking industry, it was found that the presence of aluminum rendered the alloy more resistant to oxidation, and that the presence of copper rendered the alloy more resistant to the corroding influences of the acids or other reagents present or generated during the operation of petroleum cracking.

The preferred composition of the new alloys is :Chromium, from about 4 percent to about 8 percent; copper, about 0.5 percent; aluminum, about 1.0 percent; with or without minor quantities of other elements; balance of iron.

I claim:

In petroleum cracking, carrying out the cracking operations in apparatus composed of 48% chromium, .25-.5% copper, .51% aluminum, with the balance chiefly iron, there being freedom from other elements in an amount more than that classified as impurity.

In testimony whereof, I have hereunto subscribed my name this 4th day of February,

VERE B. BROWNE. 

